i7 2600K 3.4Ghz vs i5 7600K 3.8Ghz

This is probably a “Can Cubase use all 8 Intel CPU threads?” question.

For my project studio machine for music making mainly using a lot of soft synths.

i7 2600K 3.4Ghz (2011 release 8MB cache ) - 4 core - 8 threads

i5 7600K 3.8Ghz (2017 release 6MB cache) - 4 core 4 threads

The old i7 is in a PC I have at the moment which I am wondering should be upgraded
to a new i5 (7th gen) machine. In the main the change is to utilize 64 bit Cubase over the 32 bit
running on that machine now. (64 bit Windows)

I am planning going 64bit Cubase, the new machine would be i5 64 bit Windows 10 and if I keep what I have (i7 2600) I will do a clean Windows 7 64 bit install.

Given my projects tend to use about 50pct cpu using the i7 I wonder if the i5 “upgrade?” (an entire new build audio specific custom audio PC) might be an fools errand for virtually zero CPU performance gain.

If anyone has any ideas about Cubase and Intel CPU thread utilization of Cubase 8/9 that would be great. (I suspect it may also rely on multi thread synths I use such as Diva and Lu-SH-101 as examples which can both make use of multi-threading) though to be fair most I use don’t as far as I know.

Thanks for replies in advance. (I am suspecting the difference in CPU performance gain would be marginal)

The 4 virtual cores dont count for realtime audio. Therefor the cache and clockspeed are leading if u want to choose.
The virtual cores can do non real time work like refreshing windows and parameters etc.